A fuel-wave rectifier device is known from the journal "IEEE Transactions on Magnetics", Vol. 27, No. 2, March 1991, pages 2333-2336, which includes a primary winding and two secondary windings disposed in parallel and wound in mutually opposite directions and connected to a superconducting coil for charging it. Each of the secondary windings is constituted by 1610 superconducting wires connected in parallel and organized in 230 strips of seven wires each.
The strips are connected together in groups of ten. thus making up 23 parallel-connected groups each of 7.times.10 wires in parallel, together constituting a single superconductor.
For one of the secondary windings, this superconductor is helically wound on the outside surface of a cylinder over 11/23-rds of a turn, and for the other is wound in the opposite direction over 12/23-rds of a turn on the inside surface of the cylinder inside which the primary winding is to be found.
Each of the secondary windings is fitted with two heater elements each occupying a small width, 5 mm, of the superconductor that forms the winding: one heater element on each face of the superconductor. A heater element is constituted by a plurality of turns of manganin wire.
Those heater elements serve to change the conductivity state of the two superconductors constituting the secondary windings feeding the superconducting coil to be charged.
That provides one example of a superconducting switch. However such a disposition suffers from certain drawbacks:
the need to place the heater elements around the superconductor makes switches complicated to implement; PA1 since the heater elements and the superconductor are not at the same electrical potential, it is necessary to provide good electrical insulation between them; and PA1 the need to have good thermal insulation between the superconducting switch and the helium increases recovery time, and therefore, in the example of the above article which relates to a rectifier for charging a superconducting coil, the maximum operating frequency of the rectifier is reduced. Thus, in that article, the maximum frequency is not more than 0.5 Hz.